Keccak-256 Hash Calculator

Keccak-256 is a cryptographic hash function that produces a 256-bit (32-byte) message digest. It was designed by Guido Bertoni, Joan Daemen, Michael Peeters, and Gilles Van Assche, and won the NIST hash function competition in 2012.

While Keccak was selected to become SHA-3, there is an important difference between "Keccak-256" and "SHA3-256": they use different padding schemes. The original Keccak uses simple multi-rate padding (pad10*1), while NIST's SHA-3 standard adds domain separation bits (0x06 for SHA-3, 0x1F for SHAKE).

Key characteristics of Keccak-256:

• Based on the sponge construction with a 1600-bit state

• Uses the Keccak-f[1600] permutation with 24 rounds

• Rate of 1088 bits and capacity of 512 bits for 256-bit security

• Resistant to length extension attacks

Keccak-256 is most famously used by Ethereum and other blockchain platforms:

• Ethereum address generation from public keys

• Transaction and block hashing

• Smart contract function selectors (first 4 bytes of Keccak-256 hash)

• Merkle tree construction for state management

When working with Ethereum, always use Keccak-256 (not SHA3-256) as the platform adopted Keccak before the SHA-3 standard was finalized with its modified padding.